On Mon, Jul 29, 2019 at 01:17:27PM +0800, Li Wang wrote: > Hi Naoya and Linux-MMers, > > The LTP/move_page12 V2 triggers SIGBUS in the kernel-v5.2.3 testing. > https://github.com/wangli5665/ltp/blob/master/testcases/kernel/syscalls/ > move_pages/move_pages12.c > > It seems like the retry mmap() triggers SIGBUS while doing the numa_move_pages > () in background. That is very similar to the kernel bug which was mentioned by > commit 6bc9b56433b76e40d(mm: fix race on soft-offlining ): A race condition > between soft offline and hugetlb_fault which causes unexpected process SIGBUS > killing. > > I'm not sure if that below patch is making sene to memory-failures.c, but after > building a new kernel-5.2.3 with this change, the problem can NOT be reproduced > . > > Any comments? > > ---------------------------------- > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -1695,15 +1695,16 @@ static int soft_offline_huge_page(struct page *page, > int flags) > unlock_page(hpage); > > ret = isolate_huge_page(hpage, &pagelist); > + if (!ret) { > + pr_info("soft offline: %#lx hugepage failed to isolate\n", > pfn); > + return -EBUSY; > + } > + > /* > * get_any_page() and isolate_huge_page() takes a refcount each, > * so need to drop one here. > */ > put_hwpoison_page(hpage); > - if (!ret) { > - pr_info("soft offline: %#lx hugepage failed to isolate\n", > pfn); > - return -EBUSY; > - } Sorry for my late response. This change skips put_hwpoison_page() in failure path, so soft_offline_page() should return without releasing hpage's refcount taken by get_any_page(), maybe which is not what we want. - Naoya
